Biochemical and physiological bases for utilization of dietary amino acids by young Pigs

Abstract

Protein is quantitatively the most expensive nutrient in swine diets. Hence it is imperative to understand the physiological roles played by amino acids in growth, development, lactation, reproduction, and health of pigs to improve their protein nutrition and reduce the costs of pork production. Due to incomplete knowledge of amino acid biochemistry and nutrition, it was traditionally assumed that neonatal, post-weaning, growing-finishing, and gestating pigs could synthesize sufficient amounts of all "nutritionally nonessential amino acids" (NEAA) to support maximum production performance. Therefore, over the past 50 years, much emphasis has been placed on dietary requirements of nutritionally essential amino acids as building blocks for tissue proteins. However, a large body of literature shows that NEAA, particularly glutamine, glutamate, arginine and proline regulate physiological functions via cell signaling pathways, such as mammalian target of rapamycin, AMP-activated protein kinase, extracellular signal-related kinase, Jun kinase, mitogen-activated protein kinase, and NEAA-derived gaseous molecules (e.g., nitric oxide, carbon monoxide, and hydrogen sulfide). Available evidence shows that under current feeding programs, only 70% and 55% of dietary amino acids are deposited as tissue proteins in 14-day-old sow-reared piglets and in 30-day-old pigs weaned at 21 days of age, respectively. Therefore, there is an urgent need to understand the roles and dietary requirements of NEAA in swine nutrition. This review highlights the basic biochemistry and physiology of absorption and utilization of amino acids in young pigs to enhance the efficacy of utilization of dietary protein and to minimize excretion of nitrogenous wastes from the body.

Dietary l-leucine supplementation enhances intestinal development in suckling piglets

“…Beginning at 7 days of age, production of milk by sows becomes a limiting factor for maximal growth of piglets (Rezaei et al 2013). It is noteworthy that l-leucine supplementation increased the growth of sow-reared piglets between 7 and 21 days of age (Table 2).…”

“…Milk contains a high content of l-leucine (Davis et al 1994;Wu and Knabe 1994). Effects of supplementing l-leucine to milk on breastfed neonates are unknown (Rezaei et al 2013;Wu 2014).…”

Within-litter variation in birth weight: impact of nutritional status in the sow

“…These amino acids are substrates for the synthesis of glutamate and arginine, and, therefore, alanine, citrulline, arginine, and proline in pigs (Rezaei et al, 2013a) and ruminant species . Data from our laboratories suggest that dietary supplementation with BCAAs throughout pregnancy can reverse IUGR in a rat model of malnutrition (Zheng et al, 2009).…”

Dietary supplementation with l-glutamate and l-aspartate alleviates oxidative stress in weaned piglets challenged with hydrogen peroxide

“…Results of recent studies indicate beneficial roles of Glu and Asp in improving nutrition, anti-oxidative capacity, and immunity under physiological and pathological conditions (Feng et al 2014;Rezaei et al 2013b;Wu et al 2015a, b, c). Glu and Asp are extensively metabolized in intestinal epithelial cells to yield adenosine triphosphate (ATP) in enterocytes (Rezaei et al 2013a), which is critical for intestinal normal absorptive and mucosal barrier function . Glu and Asp also serve as pivotal substrates for other biological active molecules, including the synthesis of glutamine, glutathione, proline, ornithine, and arginine (Ito et al 2012;Wu 2013b).…”